Jack construction



March 5, 1946. 1A. KAIS 2,396,103

JACK CONSTRUCTION Filed Feb, 16, 1945 j [may I INVENTOR.

Patented Mari 1946 UNITED STATES PATENT OFFICE, I 2,396,103 V JACK CONSTRUCTION Achille Kais, Detroit, Mich. L Application February 16, 1945, Serial No. 578,239

3 Claims. (.01. 254-111) This invention relates to lifting jacks, the primary object of theinvention beingto provide a lifting jack including liftingand holding pawls operated by a vertically swinging lever, thereby providing a jack requiring appreciably less power for the operation thereof, thanis required in the operation of the well known screw-type jack.

An important object of the invention is to simplify the construction of the pawls, and the spring controlling the pawls, the simplification of the spring and pawl construction, reducing the cost of production by reducing the number of parts, required in the manufacture of the jack.

A further object of the invention is to provide a lifting jack wherein the lifting power directed to the jack, is applied directly under the head load, providing a more direct lift than is possible with jacks of known construction. Still another object of the invention is to provide a trip pawl mounted in such a way that the action of the lifting and holding pawls of the jack may be reversed and automatically controlled by the rocking movement of the operating lever, reversing the action of the jack to lower the lifting bracket and its load.

With the foregoing and other objects in View which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter more fully described and pointed out in the structed in accordance with the invention, parts thereof being shown in section.

Figure 2 is a sectional view taken approximately on line 2-2 of Fig. 1.

Figure 3 is an elevational view illustrating the reversing pawl as operated to lower the lifting head of the jack.

walls, for the reception of therack bar I which is substantially T-shaped in cross-section. In

order that the rack'bar 1 may be removably secured to the base, a cotter key indicated at 8 is providedand extendedthrough registering open ings in the rack bar and flange 6.

The rackbar I, provides a support for the load I porting arm H, at a point below the bracket I0,

Figure 4 is a fragmental elevational view illus of the lifting pawl of a being such that the inner end thereofmay extend where the forked end l3 of the lever i4 is pivotally connected. As clearly shown by. Fig. 2 of the drawing, the forked end of the lever l4, straddles the rack bar and load head, to the end that movementof the lever M will be balanced, preventing twisting of the jack when pressure is brought to bear on the lever, in the operation of the jack.

The holding pawl is indicated by the reference character l5and embodies side-arms which are connected at their free ends by a connecting bar It, which connectingbar is adaptedto engage the teeth I] of the rack bar. The arms of the holding pawl l5 are curved inwardly towards the rack bar so that the contact between the connecting bar and the teeth of the rack bar, will be at a point below the pivot l8 of the holding pawl 15.

Pivotally mounted within the forked end of the lever 14, is a lifting pawl [9 which also embodies curved arms connected at their free ends by means of a connecting bar 20.

The pawls l5 and [9 are normally urged towards' the teeth of the rack bar I, by means of the spring 2! which is shown as secured to the arm ll of the load head 9, the spring being extended downwardly and upwardly between the arms of the pawls, where it contacts the connecting bars of the pawls, normally restricting moveto a point directly over the curved edge. Thus it will be seen that when the screw pin 24 has been positioned as shown by Fig. 2 of the drawing, and the lever is moved upwardly, the upper end of the reversing pawl will be swung outwardly, while the lower end thereof will move into engagement with the connecting bar 20 of the lifting pawl I9, forcing the pawl I9 away from the teeth of the rack bar engaged thereby. The lever I4 is now pressed downwardly with the result that the screw pin 24 will now move downwardly over the curved edge of the reversing pawl, allowing the pawl I9 to move into contact with the rack bar. As the reversing pawl moves so that the upper end thereof contacts the holding pawl I5, the holding pawl will be moved out of engagement with the rack bar, allowing the load head to drop into the adjacent lower space between teeth of the rack bar. By repeating this operation, the load head may be moved to its lowermost position to release .it from the load.

On operating the jack to elevate the load head in jacking up a load, the screw pin is removed, and the reversing pawl 22 remains in the position as shown by Fig. 1 of the drawing. With the reversing pawl in this position, it will be seen that when the lever I4 is pressed downwardly, the load head is elevated or raised on the rack bar. It follows that because of the spring pressure against the pawl IS, the pawl I5 will move into a notch or recess between teeth of the rack During the upward movement of the lifting head, the weight of the load is supported by the lifting pawl 19. The .lever I4 is now elevated, with the result that the pawl I9 moves over the teeth of the rack bar and again moves into a notch or recess between adjacent teeth. Upon downward movement of the lever the load head is again elevated, the pawl I5 again taking a position in a notch or recess of the rack bar above the previous point of contact with the rackbar by the pawl. As this operation is continued, the load head is elevated to the desired position.

In view of the foregoing detailed disclosure, it is believed that a further description as to the operation of the jack is unnecessary.

What is claimed is:

1. In a jack, a vertical rack bar, a movable load head mounted for movement longitudinally of the rack bar, a load-engaging bracket forming a part of the load head, a lever having a forked end adapted to straddle the rack bar and load head, means for pivotally connecting the forked end of the lever to the load head at a point directly under the bracket, a pivoted lifting pawl mounted on the forked end of the lever at a point spaced from the pivoted end of the lever, a holding pawl pivotally mounted on the load-engaging bracket, means for normally urging the pawls into engagement with the teeth of the rack bar moving the load head longitudinally of the rack bar when the lever is rocked vertically, a reversing pawl mounted on the load head, said reversing pawl adapted to alternately move the lifting pawl and holding pawl out of cont-act with the teeth of the rack bar when the lever is rocked vertically, thereby lowering the load head, and a removable pin extending from the lever and adapted to engage the reversing pawl, operating the reversing pawl.

2. In a lifting jack, a vertical rack bar, a movable load head mounted on the rack bar, an operating lever pivotally connected with the load head, a lifting pawl connected with the lever, a

holding pawl mounted on the load head, a double-ended reversing pawl mounted on the load head, said reversing pawl having a curved edge, a pin carried by the lever and adapted to move over the curved edge of said reversing pawl, alternately moving the ends of the reversing pawl into engagement with the lifting pawl and holding pawl as said lever is rocked vertically, whereby said lifting pawl and holding pawl are alternately moved into engagement with the teeth of the rack bar, lowering the load head.

3. In a lifting jack, a vertical rack bar, a movable load head mounted on the rack bar, an operating lever pivotall connected with the load head, a lifting pawl connected with the lever, a holding pawl connected with the load head, a spring engaging the pawls and adapted to urge the pawls into engagement with the teeth of the rack bar, a double-ended reversing pawl mounted on the load head and adapted to alternately move the lifting pawl and holding pawl out of engagement with the rack bar, and means carried by the lever for operating the double-ended pawl when the lever is rocked, lowering the load head.

ACHILLE KAIS. 

